Image decoding apparatus and image coding apparatus

Abstract

Delay based on WPP processing is reduced. An image decoding apparatus ( 31 ) includes: a prediction image generation unit ( 308 ) by using decoded data from a first position to a second position, the first position being, in a CTU row immediately above a CTU row including a target CTU, identical to a position of the target CTU, the second position being a position one CTU forward relative to the first position; and an entropy decoding unit ( 301 ) that performs decoding of the target CTU by using the decoded data from the first position to the second position, the first position being, in the CTU row immediately above the CTU row including the target CTU, identical to the position of the target CTU, the second position being a position one CTU forward relative to the first position.

1 . An image decoding apparatus for decoding a flag indicating whether or not Wavefront Parallel Processing (WPP) is performed, and decoding a picture based on the WPP, the image decoding apparatus comprising:
 a prediction parameter decoding circuit configured to determine whether or not a neighboring region is available for a target region; and   a prediction image generation circuit configured to generate a prediction image by using an intra prediction referring the neighboring region,   wherein the prediction image generation circuit generates the prediction image by referring an image up to a position xCTU+wCTU*1−1 in a line above the target region,   wherein the xCTU is an x coordinate of the target region, and the wCTU is a width of the neighboring region.   
     
     
         2 . An image coding apparatus for coding a flag indicating whether or not Wavefront Parallel Processing (WPP) is performed, and coding a picture based on the WPP, the image coding apparatus comprising:
 a prediction parameter coding circuit configured to determine whether or not a neighboring region is available for a target region; and   a prediction image generation circuit configured to generate a prediction image by using an intra prediction referring the neighboring region,   wherein the prediction image generation circuit generates the prediction image by referring an image up to a position xCTU+wCTU*1−1 in a line above the target region,   wherein the xCTU is an x coordinate of the target region, and the wCTU is a width of the neighboring region.